Conventionally, a stereoscopic photograph obtained by viewing two photographs photographed from two points separated right and left separately with right and left eyes of a viewer has existed for many years. Techniques for an electronic imaging device, an electronic display, a digital signal processing, or the like have greatly developed recently, thereby making photographing, recording, transmitting and displaying of electronic stereoscopic images easy, so that implementation of stereoscopic television broadcasting has become more likely.
Various systems have been proposed for stereoscopic displaying performed by an electronic display, but two eyes stereoscopic viewing (a system where a pair of images for right and left are displayed in a superimposing manner (3D) by utilizing linear polarized lights orthogonal to each other regarding right and left or circularly-polarized lights opposed to each other regarding a rotating direction, and the right and left images are viewed separately using linearly-polarizing glasses for linear polarized lights orthogonal to each other regarding right and left or circularly-polarizing glasses for circularly-polarized lights opposed to each other regarding a rotating direction) is most realistic.
In the two eyes stereoscopic viewing, however, such a fact is described in paragraph [0009] in Patent Document 1 described below that it is difficult to optimally adjust a stereoscopic viewing state (a fused state of right and left images). Further, the following descriptions are included in paragraphs [0067] and [0068] in the Patent Document 1.
In the paragraph [0067] , there is a description “. . . a case that an image is seen on a small screen 15A is different in projecting amount and depth amount from the same image is seen on a large screen 15C . . . ”.
In the paragraph [0068] , there is a description “in view of these circumstances, assuming a stereoscopic display device finally utilized, an index is provided so that confirmation can be made at a display section 9 in order that a projecting amount and a depth amount do not exceed a limit projecting amount and a limit depth amount of the stereoscopic display device. The index can be formed utilizing an actual body or it may be formed utilizing a stereoscopic image. In the stereoscopic display device assumed, data for a typical stereoscopic display device may be used, or data may be selected or set by a user.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-264851
If the stereoscopic camera disclosed in Patent Document 1 is used for photographing in reproduction of a stereoscopic image, adjustment limit points must be set to both of a distant view and a near view (see paragraphs [0070] to [0072] in Patent Document 1), but Patent Document 1 does not include any description about a principle of setting limit points for the distant view and the near view and a reference for the setting. Accordingly, respective photographing must depend on individual photographer intuition, therefore each photographer is required to have high-level skill. From the description “. . . in the stereoscopic display device assumed, data for a typical stereoscopic display device may be used, . . . ” in the patent document 1, the stereoscopic image data obtained by such photographing is thought to act on only a specified display at a viewing time effectively. It is impossible to use such a stereoscopic camera in a versatile manner.
In most of “stereoscopic televisions” actually used at an exhibition or the like, such a case often occurs that an infinite subject image such as a far mountain only appears within about one meter positioned from a display surface of a display in a depth direction. That is, in such a stereoscopic television, an object which should originally appear at an infinite position appear at a position within about one meter (several tens centimeters in some cases) from a display screen of the stereoscopic television in a depth direction, and all the other objects appear before the object. As a result, a viewer feels as if he/she was seeing a miniature set.
As shown in FIG. 8A, assuming that a distance between both eyes of a human (or an interpupillary distance) is represented as Bs and a viewer watches a stereoscopic television where a distance between right and left images of an infinite subject is displayed as a distance of the illustrated bs=Bs/2 from a position spaced from the stereoscopic television by 2 meters, an infinite stereoscopic image in a stereoscopic viewing appears at a position spaced from the viewer by 4 meters, because, when a viewing distance is represented as DA and a distance feeling on a stereoscopic viewing field is represented as DT, DT=2000/(1−32.5/65)=4000 mm is obtained from a relationship of DT=DA/(1−bs/Bs).
FIG. 8B represents a state that a viewer watches the stereoscopic television illustrated in FIG. 8A from a viewing distance of 1 meter, where the distance feeling of an infinite stereoscopic image according to FIG. 8B appears at a distance of DT=1000/(1−32.5/65)=2000 mm, namely, 2 meters. When a stereoscopic image set to be narrower than an interpupillary distance of a human is viewed, the phenomenon described above occurs necessarily.
Therefore, it is required that a viewer can obtain a natural depth feeling close to the reality and an infinite distance feeling or the farthest distance feeling within a display screen appears naturally even if a viewing distance varies. It is necessary to avoid such a feeling that a viewer sees a miniature set. An object of the present invention is to solve these problems to realize stereoscopic television broadcasting.